Be warned if you plan on traveling - notably flying - during the holidays. Experts are predicating "flat traffic" for the remainder of the holiday season. The "flat traffic" is largely due to the demand for flights is easing. 47.2 million passengers are expected to traffic during the holidays, down from 47 million who traveled last year. Because this, airlines are cutting the number of flights, which could lead to canceled flights.

"Despite signs of slowing in the economy and sky-high energy prices, we expect to see another strong season of holiday air travel," ATA President and Chief Executive James May said in a release.

The four busiest days during the winter travel period are expected to be Jan. 2, Dec. 21, Dec. 27, and Dec. 26, with each averaging more than 2.5 million passengers. The ATA expects Christmas and Christmas Eve, each with an average of 1.9 million passengers, will the least busy.

Robert Mann, an airline consultant in Port Washington, N.Y., said the forecast shows demand on the days farthest away from the actual holidays has declined and that airlines have scaled back their capacity to match that.

Like they did for the busy Thanksgiving travel period - when the ATA forecast a 4 percent traffic increase - airlines have added staff, extra self-service kiosks and other enhancements to terminal and gate areas. And when delays do happen, carriers will let customers know via wireless devices up to 24 hours in advance.

The trade group advised passengers to plan for longer-than-usual security lines, especially on the busiest travel days, and to pack any gifts unwrapped to ease inspections.

The passenger forecast comes as a large winter storm settled in across the Northeast, and airlines urged travelers to expect delays and reschedule trips involving the high-traffic region. Delta Air Lines Inc. and Continental Airlines Inc. were permitting customers to change affected flights without penalty.